Pest control system

ABSTRACT

A method of pest control which includes heating the affected area to a temperature which is lethal for the pests being exterminated, and maintaining this elevated temperature in the zone for a predetermined period of time. The treatment is undertaken after determining the air flow parameters for the treatment zone, so as to be able to determine the CFM requirements for achieving a requisite air flow rate of between 0.5 and 70 air changes per hour in the treatment zone. Heated air is introduced to the treatment zone at the requisite air flow rate and at an initial temperature of at least about 240° F., with the temperature in the treatment zone being elevated at a predetermined rate until the air temperature reaches a predetermined set point. Once the predetermined set point temperature is reached within the treatment zone, the introduced heated air is adjusted to an eradication temperature and maintained in such a condition for a predetermined period of time sufficient to eradicate respective pests within the treatment zone.

FIELD OF THE INVENTION

The present invention relates generally to a method for exterminatingpests by thermal treatment of enclosed pest-occupying zones, wherein thezone is treated with heated air under controlled conditions for a periodof time sufficient to achieve extermination of the pests. The term“pests” is intended to refer generally to creatures such as insects,mammals, reptiles, and the like, but may also include some otherundesirable but non-toxic forms of matter such as certain types ofbacteria, molds, and viruses.

BACKGROUND OF THE INVENTION

In the past, various techniques have been employed to exterminate pests,including the introduction of toxic or lethal gases, such as those usedin typical fumigation techniques including methyl bromide, phosphine, orthe like. These techniques involve certain risks to personnel, as wellas to the environment, and hence are not readily undertaken withoutnecessary precautions. Some are environmentally unfriendly. On the otherhand, the present invention involves a technique for treating the zoneor area thermally, with this technique being effective while creatinglittle if any danger to the ambient atmosphere or the environment.Delays resulting from extended periods of venting are also avoided.

The technique of the present invention is adaptable for use in a widevariety of structures and enclosures. This includes zones which aresituated within older structures, as well as more modern structures. Themagnitude of the volume requiring treatment poses few problems orlimitations, while it is appropriate that the heat generating equipmentbe properly sized. Also, the process may be undertaken utilizingconventional fuels including natural gas, propane, steam, electricity,or combinations thereof.

It has been discovered that the extermination and sterilization processof the present invention is useful in many different applications. Eachof such applications require a unique set of operating parameters foreffectively treating the target pests. As such, it is desirable toadjust relevant operating conditions to provide an effective yet energyefficient eradication system.

Certain applications, such as food sterilization processes, have beenfound to respond to thermal eradication parameters substantiallydifferent than that proposed in previously developed systems. As such,it is a primary object of the present invention to provide a thermalpest control system that is particularly adapted to treat pests in avariety of applications with a high degree of efficiency.

SUMMARY OF THE INVENTION

In accordance with the present invention, a technique is providedwherein heat is provided utilizing heated air, with the heated air beingdelivered or discharged to the treatment zone at a variable temperatureand at a volume rate sufficient to achieve between about 0.5 and 70 airchanges per hour. The variable discharge air temperature is preferablyprovided to most efficiently and quickly reach and maintain a targeteradication temperature within the treatment zone. As such, heated airis preferably initially discharged to the treatment zone at atemperature of about 240° F. at a desired volume rate. Once the desirederadication temperature, such as at least about 120° F., is reached, thedischarge temperature from the heating unit is lowered to a desiredtemperature set point for a predetermined period of time necessary toachieve a 100% treatment effectiveness.

Additionally, the treatment zone temperature is ramped-up from thenormal temperature at a desired rate to reach a temperature sufficientlyhigh to be lethal to the relevant pests. The ramp-up temperature ratemay be set at, for example, about 10° F. per hour, with this ramp-uprate being sufficient to trap pests, particularly mammals or reptilesbefore they are able to escape the zone. Higher or lower temperatureramp-up rates, however, may be employed, as desired per application. Theramp-up temperature rate must also be maintained below a predeterminedupper threshold in order to avoid structural damage due to inducedthermal stresses within the treatment zone.

The term “lethal temperature” is intended to refer to a temperaturewhich is sufficient to provide a kill for the pest. In this connection,a temperature of about 120° F.-130° F. is generally adequate, howeversome pests may require a slightly higher temperature to be effective.

While other heating equipment may be employed, direct-fired heaters arepreferable. Additionally, for the process and technique to be effective,the temperature of air discharged into the treatment zone should bevariable, as described above.

A ramp-up rate of up to about 10° F. per hour is most desirable, thoughhigher temperature ramp-up rates are contemplated by the presentinvention as being useful in certain applications. Typically, an upperlimit to temperature ramp-up rates is desired in order to preservestructural integrity of the building or enclosure. Rates substantiallyin excess of about 10° F. per hour may result in adverse effects to thestructure and its overall integrity. By controlling the ramp-up ratewithin a safe range, therefore, it is possible to both trap and kill thepests in hard-to-reach places, as well as reducing the impact of adverseaffects due to induced thermal stresses.

In addition to a complete kill of existing pests, the elevatedtemperatures provided in the treatment zone by the system of the presentinvention may be effective for the destruction of any eggs, larvae,pupae that may be present. Test cages may be employed to determineeffectiveness of the overall thermal treatment.

The use of heated air with a certain portion originating from outsidethe treatment zone provides an added advantage in the exterminationtechnique. It has been found that certain pests may be able to withstandelevated temperatures when the relative humidity within the treatmentzone is relatively high. The utilization of at least some outside air iseffective in holding the relative humidity of the treatment zone down toa point where the pests are not given this added measure of protection.The use of some heated outside air is also advantageous in that watervapor present within the treatment zone is being continuously drivenfrom the zone, without being retained and/or accumulated as would be thecase in a system employing full recirculation.

However, it has been found that certain applications of the pest controlsystem of the present invention respond more desirably through the useof at least partially re-circulated air. The use of re-circulated airtypically results in higher moisture content within the treatment zone,which is preferable, for example, in wood packaging heat treatmentsystems. In addition, the use of re-circulated air within the treatmentzone accelerates the temperature ramp-up rate, and minimizes the powerneeded to heat the discharge air. As such, the use of re-circulated airfrom within the treatment zone both adds effectiveness of certainapplications to the system, and enhances efficiency of the system.

Therefore, it is a primary object of the present invention to provide animproved technique for extermination of pests through thermal treatment,with the treatment utilizing predetermined mixtures of outside and/orre-circulated air heated at a variable discharge temperature for maximumeffectiveness and efficiency.

It is a further object of the present invention to provide an improvedtechnique for the extermination of pests including insects, mammals suchas rats, mice and the like, as well as reptiles, wherein the techniqueis undertaken thermally so as to avoid use of toxic gases which may poseenvironmental as well as personnel hazards.

It is a still further object of the present invention to provide animproved technique for the reduction and/or elimination of somenon-toxic forms of micro-organisms, including particular varieties ofbacteria, molds, and viruses, wherein the technique is undertakenthermally.

It is yet a further object of the present invention to provide aneffective time-expedient technique for pest extermination utilizingthermal treatment for undertaking and completing the exterminationoperation.

Other and further objects of the present invention will become apparentto those skilled in the art upon a study of the following specification,appended claims, and accompanying drawings.

IN THE DRAWINGS

FIG. 1 is a flow chart representing the major preliminary steps involvedin defining the requirements for equipment to be utilized in thecontemplated treatment process; and

FIG. 2 is a block diagram illustrating the steps to be undertaken in thepest extermination operation of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the preferred embodiment of the present invention,the thermal treatment of a zone for extermination of pests is undertakenas follows. It is believed that the recitation of steps set forth belowwill enable those of skill in the art to readily and effectivelypractice the technique.

Treatment Zone Defined

The dimensions, type of structure, as well as area of structure for heattreatment is analyzed and determined. This determination enables thetechnician to establish some basic guidelines for the equipmentnecessary to effectively handle the procedure. Accordingly, the natureof the heat source and fuel supply is determined, along with theequipment installation factors.

The step of defining treatment zone air flow is then undertaken withrespect to heat movement, air distribution, placement of the equipmentbeing utilized, and desired locations for heated air inlet anddischarge. This step may generally be characterized as the determinationof air flow parameters for the treatment zone.

Availability and adequacy of power and fuel supply for the heatingsystem being employed is then determined. The requirements of the fuelsupply are established by the energy available at the treatment sitesuch as natural gas, propane, steam, electricity, or combinationsthereof.

As a preliminary step, the treatment zone is analyzed and used todetermine the BTU requirements. Through this step, the specific heatloss calculations may be made in order to more specifically determinethe quantity and size of equipment necessary, including heaters, fans,ductwork, and the like. Placement of equipment may then be readilydetermined.

With the equipment in place, means are provided to provide heated air tobe discharged within the treatment zone at a variable temperature duringthe treating process.

As described above, the temperature discharge rate from the heatingapparatus is preferably variable within a pre-defined program. Forexample, air is preferably discharged from the heating apparatus at atemperature of about 240° F., with such air discharge temperature beingmaintained for a predetermined period of time necessary to reach atarget eradication temperature. In many embodiments, such an eradicationtemperature is between about 120 and 130° F., but certain applicationsmay require higher eradication temperatures.

In one embodiment of the invention, the discharge temperature of the airis dropped from about 240° F. to the target eradication temperature soas to maintain such eradication temperature within the treatment zonefor a predetermined period of treatment time. Such an air dischargetemperature drop may be performed through a single step-function, or mayinstead be performed through other means of temperature change. Examplesof alternative temperature change mechanisms include multiplestep-functions, integration techniques, and the like.

In some embodiments of the present invention, the air dischargetemperature profile may be automatically controlled through the use ofprogrammed software means operably coupled to controller means forcontrolling the energy input of the heater apparatus. In such a manner,a temperature profile may be pre-programmed into the software means tothereby automatically control the output of the air heater.

In a preferred example air discharge temperature profile, the initialair discharge temperature of about 240° F. is switched in a singlestep-function operation to a temperature consistent with a targetederadication temperature, such as 130° F. In other embodiments, however,the air discharge temperature may be changed from an initial temperatureof about 240° F. prior to reaching the steady-state eradicationtemperature within the treatment zone, such that the temperature withinthe treatment zone gradually stabilizes at a set point temperature,rather than initially overshooting the target eradication temperatureand gradually decreasing to the target eradication temperature. A widevariety of other temperature profiles may be utilized by the variableair discharge temperature aspect of the present invention.

A particular advantage introduced by the variable air dischargetemperature is in enhancing the efficiency of the system. In particular,significant energy is required to heat air to the temperatures requiredto eradicate pests. As a result, significant cost and energy savings arereaped by minimizing the air discharge temperature where possible. Inthis case, it has been found that a target eradication temperature needonly be maintained for the predetermined period of time to accomplish a100% pest treatment. Accordingly, temperatures within the treatment zoneneed not exceed the target eradication temperature for any extendedperiod of time. The variable air discharge temperature profile of thepresent invention, therefore, significantly enhances efficiency withoutcompromising pest eradication effectiveness.

It has further been found that the heated air flow rate through thetreatment zone may be set according to the particular application beingtreated. For example, off-gassing treatment typically requires anoperating temperature of 260° F., and an air exchange rate of 50-70 perhour. On the other hand, drying and mold remediation have been found tobe most effective at a significantly lower air exchange rate of betweenabout 0.5 and 3air changes per hour. In the above examples, the term“air exchange” refers to a volume of air output from the heater system,with one air exchange being equal to the volume of air within thetreatment zone.

The adjustment of heated air output volume is preferably set at aminimum rate that enables a 100% eradication effectiveness. As a result,efficiency of the system of the present invention is further enhanced,due to the fact that excess heated air is not driven through thetreatment zone and is, consequently, not needed to be manufactured.

A further aspect of the present invention is in the tailoredmodification of proportion of outside air to re-circulated air as inputto the air heater apparatus. As described above, certain applicationsare tolerant to, and/or require elevated moisture environments duringthe thermal treatment process. As a result, certain embodiments of theinvention preferably utilize at least some re-circulated air from withinthe treatment zone as input feed to the air heater discharge apparatus.Since re-circulated air typically maintains a relatively higher moisturecontent, the use of re-circulated air can contribute to maintaining anelevated moisture content within the treatment zone.

Moreover, the user of recycled air from within the treatment zoneminimizes the amount of energy required to heat outside air to a desiredair discharge temperature. The use of at least some re-circulated air,therefore, has the effect of either accelerating temperature ramp-uprate within the treatment zone, or minimizing the amount of energy inputby the air heater apparatus into the feed air to reach a desired outputtemperature. In some embodiments, up to about 50% of the air supply tothe heater apparatus is from within the treatment zone as re-circulatedair. The remainder of the supply air preferably is sourced from outsidethe treatment zone.

Heat is provided to the air until a temperature of at least about 240°F. is reached and it is then discharged at a volume rate sufficient toramp-up the temperature within the zone at a predetermined rate. In someembodiments, such a ramp-up rate is about 5-10° F. per hour. The volumerate is selected to be sufficient to provide for between about 0.5 and70 air changes per hour within the treatment zone. This discharge andramp-up rate is continued until an air temperature at least equal to thelethal temperature for the pests is achieved throughout the treatmentzone. Generally, a temperature of about 120° F.-130° F. is satisfactoryand constitutes an appropriate lethal temperature. The requisitetemperature and air flow rate is maintained to continue providing lethaltemperatures for a predetermined period of time. For some more resistantinsects, such as lesser grain borers, as may be found in and aroundgrain storage elevators and the like, the elevated temperature and airchange cycles are preferably maintained for periods ranging from betweenabout eleven hours and 24 hours. Upon reaching the desired treatmenttime, the heat is turned-off, and with outside air, the flow iscontinued for a gradual cool-down.

In order to provide a further means of determining that a sufficientlethal or elevated temperature is reached, and that the lethaltemperature has been achieved for a sufficient period of time, testcages may be set in place throughout the treatment zone and monitoringof these test cages will normally be adequate to indicate the totaleffectiveness of the kill.

Through such a method, pests such as insects, mammals, reptiles, and thelike may be effectively exterminated from within the treatment zone.Furthermore, some non-toxic varieties of household bacteria, molds, andviruses that are vulnerable to temperatures contemplated in processespursuant to the present invention may also be reduced and/or eliminatedvia such a thermal treatment method. Additionally, such a method mayalso be effective in accelerating respective outgassing rates of somesubstances located within the treatment zone.

It will be appreciated, of course, that various modifications may bemade in the steps undertaken and defined hereinabove, without actuallydeparting from the spirit and scope of the invention.

1. Pest extermination by thermal treatment of enclosed pest-occupyingtreatment zones comprising the steps of: (a) determining air flowparameters for the treatment zone; (b) determining CFM requirements forachieving a requisite air flow rate of between 0.5 and 70 air changesper hour in the treatment zone; (c) introducing heated air to saidtreatment zone at said requisite air flow rate and at an initialtemperature of at least about 240° F.; (d) elevating temperature in saidtreatment zone at a predetermined ramp rate until air temperature in thetreatment zone reaches a predetermined set point; (e) adjustingtemperature of the introduced heated air to an eradication temperature;and (f) maintaining said requisite air flow rate at said eradicationtemperature for a predetermined period of time sufficient to eradicaterespective pests within the treatment zone.
 2. The pest extermination bythermal treatment of enclosed pest-occupying treatment zones of claim 1wherein said eradication temperature is at least 120° F.
 3. The pestextermination by thermal treatment of enclosed pest-occupying treatmentzones of claim 1 wherein the temperature adjustment of the introducedheated air is performed in a single step-function.
 4. The pestextermination by thermal treatment of enclosed pest-occupying treatmentzones of claim 1 wherein the introduced heated air is between about 50and 100% outside air.
 5. The pest extermination by thermal treatment ofenclosed pest-occupying treatment zones of claim 1 wherein saidpredetermined set point is equal to said eradication temperature.
 6. Thepest extermination by thermal treatment of enclosed pest-occupyingtreatment zones of claim 1 wherein said predetermined set point is lessthan said eradication temperature.
 7. The pest extermination by thermaltreatment of enclosed pest-occupying treatment zones of claim 1 whereinsaid predetermined period of time is at least about 11 hours.
 8. Thepest extermination by thermal treatment of enclosed pest-occupyingtreatment zones of claim 1 wherein said predetermined ramp-up rate is upto about 10° F. per hour.